Action Mailer Delivery Observability Hook

                  ActiveSupport::Notifications.subscribe('deliver.action_mailer') do |*args|
  event = ActiveSupport::Notifications::Event.new(*args)
  mail = event.payload[:mail]

  Rails.logger.info({
    msg: 'mail.deliver',
    duration_ms: event.duration.round(1),
    message_id: mail.message_id,
    to: Array(mail.to),
    subject: mail.subject
  }.to_json)
end